Airstone and air pump questions

[Ichthys]

I recently started running a 6" airstone in my 10 gallon. My Rena 50 is running it and a Hydro 1 sponge filter. For some reason there are only a few streams of bubbles coming from the stone (if I lift the stone higher more bubbles come out, but then the filter stops). I'm using a lee's 3 way gang valve and have played around with the air control, but haven't been able to get more bubbles to come out of the stone without the filter stopping. Am I doing something wrong? How many airstones / sponge filters can the Rena 50 power?
Thanks!

 

[xray]

It sounds like your not pushing enough air. How deep is your tank. The deeper the airstone the hard the pump has to push. The rena 50 is rated for aquariums up to ten gal. Anything deeper than that and the pump can't push. If you have a 10 gal tank, then get another rena 50 to run just the airstone. If your tank is largr then you will have to get a bigger pump.

 

[partrep]

I had a similar problem with a Rena 200 running two one inch airstones. Turns out it was the fancy Penn Plax gang valve I used. It just wouldn't pass the air. I took it out and put in two old fashioned gang valves and everything works fine, provided the airstones are set at the same depth.